The invention relates to artificial mechanical hands, and more particularly to an improved mechanical hand with multiple prehension capability, especially suitable for bilaterals, or double amputees.
For unilaterals, or single amputees, a mechanical hand often takes the form of a simple split hook of the type shown, for example, in U.S. Pat. No. 1,042,413. This type of artificial hand unusually has a spring or elastic band urging the two hook sections together to grasp objects between them, with the sections openable by the action of a cable attached to a body harness. Another example of this type of artificial hand is shown in U.S. Pat. No. 1,206,753.
Bilaterals, with no natural hand for the more difficult grasping functions, need artificial hands with more complete prehension capability than is afforded by the hook described above. A number of more complex artificial hand mechanisms have been suggested, as shown for example in U.S. Pat. Nos. 2,422,530, 2,487,724, 2,409,884, 2,853,711, 3,413,658, and 4,016,607.
The disadvantages of these prior art devices have been that they are either too complicated to be economically feasible, they have been difficult to learn to operate, they have failed to provide important types of prehension capability, or they have been oriented so much toward cosmetic appeal that they necessarily have been very limited in functional advantages.
None of the devices shown in the prior patents provides the degree of prehensile versatility, with the simplicity of construction and operation, as does the present invention described below.